Bolt On Horsepower
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Instructor
Joined: Aug 2009
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From: Caledon Ont
Bolt On Horsepower
Anyone got any suggestions for some cheap bolton ponies for my L48? Will be doing it right next year just looking for some cheao spead.
I'm thinking a little ignition, no headers this year will wait till I put my rebuild in. KNN filter? any suggestions or should I just wait until I yank the boat anchor out of her?
I'm thinking a little ignition, no headers this year will wait till I put my rebuild in. KNN filter? any suggestions or should I just wait until I yank the boat anchor out of her?
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
Search is your friend on this topic 
Headers and free-flow exhaust will be your biggest power producer - no reason to wait unless you think you're going to go to angle-plug heads.
K&N is always a good idea. Ignition upgrades produce no additional power in the most common RPM range. Don't rule out the impact of a good tune!
Headers and free-flow exhaust will be your biggest power producer - no reason to wait unless you think you're going to go to angle-plug heads.
K&N is always a good idea. Ignition upgrades produce no additional power in the most common RPM range. Don't rule out the impact of a good tune!
Melting Slicks
Joined: Jul 2005
Posts: 2,545
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From: 406ci SB, AFR 180 Heads - 490 HP @5,600 RPM 529 lb-ft @ 4,100 RPM
If your plan is as you stated, to make big changes next year, don't waste your money on tiny incease of hp now. Use that extra money for better improvements next year. 
Burning Brakes
Joined: May 2009
Posts: 1,232
Likes: 6
From: Tucson AZ
St. Jude Donor '12
In addition the pragmatic suggestions above, I've always felt a 3-4 degree bump in ignition timing at idle seems to give an anemic v8 a slightly improved seat-of-the-pants feel.
Le Mans Master
Joined: Oct 2007
Posts: 7,447
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From: Tennessee/Rhode Island
A good basic tuneup, spring kit for the distributor, adjustable vacuum advance canister, a K&N airfilter, and by far, the biggest bang for the buck, a complete exhaust overhaul-2.5 inch true duals, headers of some sort (full length, block huggers, shorty etc) and free flowing mufflers (dynomax ultra flos/turbos, flow masters, Monza turbos/tips, etc). If you plan on basically a street car, especially an automatic transmission one , I would stick with block hugger/shorty headers since full length headers really only have an advantage over the other headers at really high RPM which the L-48 engine is not. As a teenager, I had a totally anemic 307 V8 in a chevy Nova and put full length headers, duals, with free flowing mufflers and the change made a TREMENDOUS difference in power, still a dog but a much stronger dog! You can easily get to a stock L-82's horsepower with these changes plus you can use the exhaust when you work/change the motor later on!
Last edited by jb78L-82; Aug 16, 2009 at 07:03 AM.
Race Director
Joined: Apr 1999
Posts: 11,520
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From: CORVETTE 77 385 C.I. TEXAS
As a teenager I bought a 307 short block for about $50 to put in a second car for an economy work car. There were a lot of witnesses & I was offered the stock 2 bl. intake for $5. so I took it. Evidently some got the idea I was going to run it!
So on the 307 test drive, I ran across a GTO that was accustomed to being beat by my Hot Rod. Seeing his opportunity to win, he went for it. Blew him away again. He was shocked
but that's what he deserved- GTO picking on what he thought was a stock 2 bl. 307! He was a good sport to keep racing & losing, but he sold the GTO after that. I never ran sto*k (a bad word to me) & did not own a 2bl. (that heavy 2bl. intake worked to prop a garage door open) so a 4 bl. that didn't miss a beat at high rpm, a solid lifter cam
& 3 spd. Hurst were installed. This was a budget work car so I used what I had (no extra headers). What I called supertuning- advanced timing, recurved dist., good spark plug wires, etc. goes w/o saying.Supertuning.
Low restriction mufflers & cat. http://www.corvettefaq.com/c3/ganeyexhaust.htm
Cam as L-48 badly needs more cam.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
Curious - why no on K&N?
I've used these exclusively for a long time, and on a 360HP 355 I saw a 14" x 4" add 4 HP over a 14" x 4" paper filter.
I hear filtration quality concerns as well - but I ran a paper sheet inside both a K&N and a quality paper filter for 3 months each and found the K&N to be pretty much perfect.
I've used these exclusively for a long time, and on a 360HP 355 I saw a 14" x 4" add 4 HP over a 14" x 4" paper filter.
I hear filtration quality concerns as well - but I ran a paper sheet inside both a K&N and a quality paper filter for 3 months each and found the K&N to be pretty much perfect.
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Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
Shorty headers generally offer litte to no power increase over the "Rams Horn" style exhaust manifolds, but give a slight bump with the "Iron Log" style exhaust manifolds.
Race Director
Joined: Apr 1999
Posts: 11,520
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From: CORVETTE 77 385 C.I. TEXAS
Bill
1 The K&N will not provide any "speed" or HP over a properly functioning stock type filter in his setup & the money would be better spent elsewhere for him.
2 I have a friend who is really into oil & oil analysis (also racing engines) "in oil analysis usually with a K&N the Fe "iron" and Si "dirt" is elevated" & "if a guy oils them up enough to filter really well, lost airflow is the result." He is not the only one who doesn't like the oil analysis results.
You may need to think about this. In general if power is increased by switching to a K&N (which can be less restrictive) then some tuning should result in the same or more power assuming the filter size is appropriate & no other restrictions.
Originally Posted by falconview
... just looking for some cheao spead....
2 I have a friend who is really into oil & oil analysis (also racing engines) "in oil analysis usually with a K&N the Fe "iron" and Si "dirt" is elevated" & "if a guy oils them up enough to filter really well, lost airflow is the result." He is not the only one who doesn't like the oil analysis results.
You may need to think about this. In general if power is increased by switching to a K&N (which can be less restrictive) then some tuning should result in the same or more power assuming the filter size is appropriate & no other restrictions.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Le Mans Master
Joined: Oct 2007
Posts: 7,447
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From: Tennessee/Rhode Island
Full-length headers increase both torque and HP at low- to mid-range RPM, especially the Tri-Y (Doug Thorely and copies) design.
Shorty headers generally offer litte to no power increase over the "Rams Horn" style exhaust manifolds, but give a slight bump with the "Iron Log" style exhaust manifolds.
Shorty headers generally offer litte to no power increase over the "Rams Horn" style exhaust manifolds, but give a slight bump with the "Iron Log" style exhaust manifolds.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
I'll note in passing this conflicts with every dyno test I've ever seen - including my own. We could split hairs and note that below 2500 RPM there's maybe a break-even at best, but 2500 on up (I would call anything between 2500 - 4500 "midrange") long-tube headers will beat any stock manifold or shorty header. Certainly you can have a too-large header diameter which leads to poor low- and mid-range flow, and of course the gain will be more up top.
Note that this is specific to the Chevy GEN I SBC and it's weak exhaust port. Every engine is different
Le Mans Master
Joined: Jul 2000
Posts: 6,664
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From: columbia city in
k+n great marketing .there are no fleets that use k+n filters .why because they let in more dirt .this topic has come up on this forum for years try the search lots of pro and cons .i am on ganeys side .
Le Mans Master
Joined: Oct 2007
Posts: 7,447
Likes: 972
From: Tennessee/Rhode Island
We'll have to agree to disagree
I'll note in passing this conflicts with every dyno test I've ever seen - including my own. We could split hairs and note that below 2500 RPM there's maybe a break-even at best, but 2500 on up (I would call anything between 2500 - 4500 "midrange") long-tube headers will beat any stock manifold or shorty header. Certainly you can have a too-large header diameter which leads to poor low- and mid-range flow, and of course the gain will be more up top.
Note that this is specific to the Chevy GEN I SBC and it's weak exhaust port. Every engine is different
I'll note in passing this conflicts with every dyno test I've ever seen - including my own. We could split hairs and note that below 2500 RPM there's maybe a break-even at best, but 2500 on up (I would call anything between 2500 - 4500 "midrange") long-tube headers will beat any stock manifold or shorty header. Certainly you can have a too-large header diameter which leads to poor low- and mid-range flow, and of course the gain will be more up top.
Note that this is specific to the Chevy GEN I SBC and it's weak exhaust port. Every engine is different
Last edited by jb78L-82; Aug 16, 2009 at 05:28 PM.
